As Vulcan prepares for war, V'Las sends a commando team to eliminate Archer, T'Pol and T'Pau, while Soval risks his sanity to warn the Andorians of the impending attack.

Two non-corporeal Organians possess the bodies of various crew members to observe humanity's reaction to tragedy. The curious beings study the response of the Enterprise crew to a fatal silicon-based viral infection contracted by Trip and Hoshi during an away mission. Phlox works feverishly for a cure. Will the "advanced" aliens learn anything about human empathy and compassion?